Upgrade to Achat 118?

[samovesel]

Hello, we need some help upgrading our PA. FIrst let me explain what kind of system we have right now.
We have 8 pieces od Achat 115 SUB A, tops are 4 pieces HK audio Linear 5 LTS A.

We ussually set bass speakers in arc array, however sometimes we do it in LR (depending on available space).
We usually set crossover at 120Hz.
Low mid frequencies are usually a bit lacking (120 – 200 Hz) so we would like to upgrade our system with adding 115 subs in the range od 90 – 180 Hz and lower the crossover point of subs.

Ok, let me explain a bit: the idea is to cross main subs (8 x 115 central or 4 x 115 per side) at 90 Hz to low mids (2 x 115 per side) and then at 160Hz to tops (2 x LTS per side).

The other idea is to use 6 Achat 118 (horns) instead of 115 subs for bass and reuse existing subs (time aligned of course) as low-mid.

So, should we just add more 115 subs or upgrade the system with 6 x Achat 118 and maybe later add two more?

Thank you.

[pysos]

Hey welcome to this forum,

So first question would be: have measured the single ways of the system and phasealigned it for
proper summation in the crossover region. Or have you simple turned the crossover-poti at your
subs to 120Hz because the LTS A playes to 120Hz -3db?
I think it`s very importend to take measurements for good phasealignment, because the LTS A System orginally
uses a BP6 Bass with a upper resonant-tuning of 80Hz which causes phase-shift and more delay in that region
than a bassreflex sub will produce.
The CUT-preset in the LTS Top needs to adress this (delayed - or a kombination of filters and phase rotation)
This means you could end up with no summation or cancellation at worst case in the crossover region.

Greetz